export function dateChange(num: number | 1, date: Date | undefined): Date {
  date = date ?? new Date();
  let timeStr = `${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()} 00:00:00`;
  let timeStamp = Date.parse(timeStr) / 1000;
  timeStamp += 86400 * num;
  return new Date(timeStamp * 1000);
}
